Method of casting aluminium alloys.



llwrrnn dramas afrnwfr I WILLIAM AJMCADAMS, OF NEW YORK, N; Y.

METHOD OF GASTING ALUIVllNIUli/l ALLOYS.

SPECIFICATION forming part of Letters Patent No. 635,053, dated October 17, 1899. Application filed September 11, 1899. fierial No. 730,110. (No specimens.)

T0 at whom, it may concern.-

Beit known that I, WILLIAM A. MoADAMs, a citizen of the United States, and a resident of the city of New York, borough of Brooklyn, in the State of New York, have invented a new and useful Improvement in the Method of Casting Aluminium Alloys, of which the following is a specification.

My invention relates to an improvement in the method of casting aluminium alloys composed of aluminium and copper and in which the metal aluminium predominates.

Aluminium when melted cools slowly, so slowly that other metals which are present in molten state in the molten aluminium are permitted to segregate and form large crystals before the slowly-cooling aluminium checks to any considerable degree their segregation and crystallization, thereby materially reducing the strength of the casting.

The object of my present invention is to prevent such segregation and crystallization of the mixture during the process of cooling, and thereby add material strength to the casting.

In an alloy composed of ninety per cent. aluminium and ten per cent. copper or similar alloys in which the aluminium forms a greater part of the alloy the hereinabove-described segregation and crystallization of the commingled metals will be liable to take place unless the molten mass is cooled so rapidly after pouring as to check the segregation and crystallization before it can have proceeded to any great extent.

By means of numerous experiments I have found that the cooling should take place rapidly within certain well defined practical limits and that the heat should be taken from the molten mass at as nearly a uniform rate as possible. This maybe accomplished when the casting is thin or small by using a metal mold of sufficient thickness to quickly remove the heat from the casting, and when the cast-' ing is to be thick or large the mold may be surrounded by a cooling medium to assist it in removing the heat with the required speed and uniformity.

To carry out my process successfully, the heat should be removed from the casting as rapidly as at the rate of one-fifth of a calory per second, and, on the other hand,- it should not be removed more rapidly than at the rate of two calories per second, as when removed more rapidly than this rate the sudden chill is found to produce the same weak structure that is produced when the heat is removedat a rate less than one-fifth of a calory per second. The best results are obtained by removing the heat at the rate of from one to one and one-tenth calories per second, a rate much more rapid than is common in the ordinary use of metallic molds. I find that this treatment of aluminium alloys in which. the aluminium forms the greater part of the alloy will increase the strength of the casting from eighty to one hundred per cent.

What I claim is- The method of casting alloys containing aluminium and copper, in which the aluminium predominates, consisting in rapidly removing the heat from the molten mass at a rate not less than one-fifth of a calory per second, viz; more rapidly than has heretofore been common in the ordinary use of molds, thereby preventing the segregation of the metals and the forination of large crystals, substantially as set forth.

In testimony that I claim theforegoing as my invent-ion I have signed my name, inpresence of two witnesses, this 9th day of September, 1899.

WILLIAM A. MOADAMS.

Witnesses:

FREDK. HAYNES, EDWARD VIEsER. 

